Build a paid HTTP seller

npm install @openx402/bazaar-sdk \
  @x402/core@2.20.0 \
  @x402/express@2.20.0 \
  @x402/stellar@2.20.0 \
  express

import express from "express";
import { bazaar } from "@openx402/bazaar-sdk";
import { HTTPFacilitatorClient } from "@x402/core/server";
import { paymentMiddleware, x402ResourceServer } from "@x402/express";
import { ExactStellarScheme } from "@x402/stellar/exact/server";

const PORT = Number(process.env.PORT ?? 4788);
const NETWORK = "stellar:testnet" as const;
const FACILITATOR_URL = process.env.FACILITATOR_URL
  ?? "https://facilitator-production-8430.up.railway.app";
const PUBLIC_URL = process.env.SELLER_PUBLIC_URL?.replace(/\/$/, "");
const PAY_TO = process.env.SELLER_PAY_TO;

// Stellar testnet native XLM Stellar Asset Contract.
const XLM_SAC = "CDLZFC3SYJYDZT7K67VZ75HPJVIEUVNIXF47ZG2FB2RMQQVU2HHGCYSC";
const PRICE_ATOMIC = "1000";

if (!PUBLIC_URL?.startsWith("https://")) {
  throw new Error("SELLER_PUBLIC_URL must be the public HTTPS tunnel origin");
}
if (!PAY_TO) throw new Error("SELLER_PAY_TO is required");

const metadata = bazaar.http({
  description: "Plays one round of rock, paper, scissors against the server.",
  serviceName: "Rock Paper Scissors",
  tags: ["game", "rps", "random"],
  method: "POST",
  body: {
    move: {
      type: "string",
      description: "Player move: rock, paper, or scissors.",
      enum: ["rock", "paper", "scissors"],
      required: true,
      example: "rock",
    },
  },
  output: {
    type: "json",
    description: "The player move, server move, and round result.",
    example: { player: "rock", server: "scissors", result: "win" },
  },
});

const facilitator = new HTTPFacilitatorClient({ url: FACILITATOR_URL });
const resourceServer = new x402ResourceServer(facilitator)
  .register(NETWORK, new ExactStellarScheme());

const app = express();
app.use(express.json({ limit: "16kb" }));

app.use(paymentMiddleware({
  "POST /play": {
    accepts: [{
      scheme: "exact",
      network: NETWORK,
      price: { asset: XLM_SAC, amount: PRICE_ATOMIC },
      payTo: PAY_TO,
      maxTimeoutSeconds: 60,
      extra: { areFeesSponsored: true },
    }],
    resource: `${PUBLIC_URL}/play`,
    description: metadata.resource.description,
    serviceName: metadata.resource.serviceName,
    tags: metadata.resource.tags,
    mimeType: "application/json",
    extensions: metadata.extensions,
  },
}, resourceServer));

app.post("/play", (req, res) => {
  const move = req.body?.move;
  if (!["rock", "paper", "scissors"].includes(move)) {
    res.status(400).json({ error: "move must be rock, paper, or scissors" });
    return;
  }
  res.json({ player: move, server: "scissors", result: move === "rock" ? "win" : "lose" });
});

app.listen(PORT, "127.0.0.1");

SELLER_PUBLIC_URL=https://your-tunnel.example \
SELLER_PAY_TO=G... \
FACILITATOR_URL=https://facilitator-production-8430.up.railway.app \
npx tsx index.ts

const weather = bazaar.http({
  description: "Returns the current weather for a city.",
  serviceName: "Weather API",
  tags: ["weather", "forecast"],
  method: "GET",
  query: {
    city: {
      type: "string",
      description: "The city to look up, such as Mumbai or London.",
      required: true,
      example: "Mumbai",
    },
    units: {
      type: "string",
      description: "Temperature units.",
      enum: ["celsius", "fahrenheit"],
      example: "celsius",
    },
  },
  output: {
    type: "json",
    example: { city: "Mumbai", temperature: 29, condition: "Sunny" },
  },
});